AbstractAs a sequence of studies to evaluate the quantity of gas evolution from low/intermediate level waste repositories,hydrogen gas evoluted from corrosion of carbon steel in simulated repository environment was evaluated by laboratory experiments. The experimental results on the hydrogen gas evolution both in air purging condition simulated oxidizing environment and nitrogen purging condition simulated reducing environment, are summarized as follows.(1)Hydrogen gas evolution enough to analyze quantitavely by gas chromatography (>5ppm) has been recognized under almost all test conditions except reducing equilibrium cement water.(2)Effects of purging gas (air,nitrogen) on the hydrogen gas evolution and the corrosion rate calculated from weight loss were air purge > nitrogen purge. On the other hand, the contribution ratio of hydrogen evolution reaction in corrosion rate was nitrogen purge > air purge.(3)Effects of test solution on the hydrogen evolution rate were as fo11ows.
• Air Purge :Equilibrium Bentonite Water ≈ Equilibrium Cement Water > Synthetic Sea Watert• N2 Purge:Synthetic Sea Water > Equilibrium Bentonite Water >> Equilibrium Cement Water(4)No distinct effect of crevice geometry of test specimen on hydrogen evolution rate was recognized. Only under the reducing equilibrium cement water, however, the increase of hydrogen evolution was confirmed after the immersion of several hundred hours.(5)Hydrogen evolution rates tended to decrease with testing time except in the reducing equilibrium cement water.(6)No distinct difference of hydrogen evolution rate between steels (SPHC, SPCC) was observed.
Hydrogen Gas Evolution from Water-dispersed Titania and Alumina Nanoparticles by γ-Ray Irradiation
